Impedance device



J. VVHYTQCZK IMPEDANCE DEVICE Filed April 18, 194-1 FIG 5 A T TORNEV Patented Dec. 29, 1942 IMPEDANCE DEVICE John Whytock, Garden City, N. Y., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application April 18, 1941, Serial No. 389,208

2 Claims.

This invention relates to electrical impedance devices and more particularly to such devices comprising a plurality of impedance units interconnected electrically and assembled in a unitary structure.

One object if this invention is to provide an impedance device that is compact, rugged and moisture resistant.

A further object of this invention is to provide an impedance device suitable for inclusion within an enclosed space such as a cable splice or the like.

Qne feature of this invention resides in the provision of a plate-like insulating support for impedance units, having secured thereto a plurality of metallic elements which serve as both electrical connectors and impedance unit securing means. I

Another feature of this invention lies in the arrangement of the impedance units on the insulating support.

Other and further objects and features of this invention will appear more fully and clearly from the following description of an illustrative embodiment thereof taken in connection with the appended drawing in which:

Fig. 1 shows one illustrative embodiment of the invention in completed form;

Fig. 2 is an elevational view of the device of Fig. 1 with part of its protective covering broken away to show interior details;

Fig. 3 is another elevational view taken at rightangles to that of Fig. 2 with the spacing between elements exaggerated for clarity;

Fig. 4 is a further elevational view taken on the opposite side of the device from Fig. 2; and

Figs. 5 and 6 show two different forms of mounting plate suitable for modified embodi-' ments of the invention.

Referring now to the drawing, I denotes the impedance device having a protective sleeve I I of fabric material thereover. A pair of flexible insulated conductors I2 and I3 serve as connecting means to the circuit in which the device is to be used. The device comprises a plurality of impedance units, for example, two as illustrated. These units may be of various types as to form and electrical characteristics. Various combinations of capacitors, inductors and resistors may be used. The two units shown in the drawing are a low positive resistance-temperature coefficient unit I4 of the type commonly called a re sistor and a high negative resistance-temperature coeflicient unit l which may be designated as a thermistor. The term thermistor is a passes through opening 22.

contraction of the words thermal resistor and designates an electrical circuit element whose electrical resistance varies widely and rapidly with change in temperature. The unit I4 may comprise a plurality of turns of resistance wire Wound on a form and covered with a protective coating. Unit I5 may comprise a disc of semiconductive material having metallic electrodes IE on either face. The semiconductive material may be a heat-treated combination of various metal oxides such as the oxides of manganese, nickel and cobalt.

The electrodes I6 may be of silver, gold or other metal applied by vapor deposition or by heating a thin layer of metallic paste applied to the disc faces, or by other suitable methods. As illustrated in Fig. 4, the area of the electrodes may be less than the whole face area of the disc. The electrode area may be varied during manufacturing to give a required over-all resistanc to the disc unit.

One way of adjusting the resistance of the disc unit by controlling the electrode area is as follows: The thermistor disc is made so that the over-all resistance of the unit is slightly low when the electrodes cover the disc faces completely. Suflicient electrode material is then ground off to bring the over-all resistance to the proper value.

Connecting leads I'I, I8 and I9, 2|] are secured respectively to the units I4 and I5 by soldering or by other suitable means.

The units are mounted on a plate 2| of insulating material such as a phenol fabric material. To mount two units of the type previously described, plate 2| is provided with a centrally located opening 22, notches 23, 24 and 25, and connectors 26 and 21 located through orifices in plate 2| and secured in place by upset or riveted flanges. Metal eyelets will serve the purpose.

The illustrated device having been described to have the two units in parallel, means for making such connections will be described. Referring to Figs. 2 and 3, leads I8 and 20 and conductor I2 are brought together on the unit I4 side of plate 2| and soldered Within connector 26. Lead 20 Referring to Figs. 3 and 4 it is seen that leads I! and I9 and conductor I3 are soldered in connector 21 entering from the thermistor unit side of the plate. Lead [1 passes around plate 2| through notch 23.

All of the leads are so proportioned that the units lie snugly against the plate 2| on opposite sides thereof. The spacing shown in Fig. 3 is as previously noted for clarity of illustration only. The conductors I2 and I3 after passing through notches 24 and 25 are twisted together. By the foregoing arrangement the electrical connections are made and the units are secured to the plate providing a substantially rigid self-supporting unit with flexible leads.

To protect the device and further maintain the units in place, a coating 28 of suitable covering material is applied over a portion of the plate, the units, the leads, the connectors and a portion of conductors l2 and 3. The extent of coverage may be as illustrated in Fig. 2. The coating 28 may comprise two layers, e. g., an inner layer of water-proofing material such as a varnish and an outer layer of material such as lacquer for mechanical protection. A piece oifabric sleeve H may be placed over the unit andt ied in place at the ends.

Other electrical combinations and physical arrangements of units may be made'in accordance with the invention. For example, the units of the device described may be connected in series by soldering leads I! and 20 together preferably in an additional sleeve connector and connecting leads l8 and E3 to conductors l2 and I3. Mounting plates such as illustrated inFigs. 5 and 6 may be provided for making up any of a plurality of difierent impedance combinations. The plates 39 maybe provided with a plurality of rows (Fig. 5) or groups (Fig. 6) of sleeve connectors 3| and an extended opening 32 or a plurality of openings 33. Edge notches may be provided as needed for carrying leads around the plate 30 or for anchoring conductors such as l2 and I3 of Figs. 1 to 4, inclusive. For any given combination of impedance units, all of the connector sleeves 3| will not necessarily be employed but an adequate numher and arrangement should be provided for all possible connections that may be made between the number of units that can be accommodated on the mounting plate.

Although the invention has been disclosed with reference to specific embodiments thereof, it Will be understood that it is not restricted thereto but limited in scope by the appended claims only.

What is claimed is:

1. A resistor device comprising two resistor units each having a pair of flexible conductive leads, a pair of insulated, flexible connecting conductors, a centrally orificed, marginally notched plate of insulating material between said units, two metallic connecting sleeves supported in openings through said plate, a lead from one resistor passing through said orifice, said lead, one conductor and lead from the other resistor being connected in one sleeve, one lead from said other i resistor passing through one of the marginal notches, said lead, the remaining conductor and the remaining lead from the one resistor being connected in the other sleeve, said conductors engaging marginal notches adjacent said sleeves, an envelope of insulating material enclosing portions of said conductors and plate andall of the other elements and a fabric sleeve covering the assembly with said conductors projecting therefrom.

2. An impedance device comprising a plurality of impedance units each having flexible conductive leads, a plurality of flexible connecting conductors, a marginally notched plate of insulating material, a plurality of metallic connecting sleeves supported in spaced openings through said plate, said leads and conductors being connected to interconnect the impedance units in a network, each lead and conductor being secured in one of said sleeves and some of the flexible interconnecting elements passing over the edge of the insulating plate through the notches to aid in securing the impedance units to said plate.

JOHN WHYTOCK. 

